Heat exchanger construction

ABSTRACT

An improved heat exchanger is disclosed. The heat exchanger is of the type including a pair of headers and a plurality of tubes extending between and fluidly connecting the headers. The improvement comprises a tubular structure for and defining in part each of said headers. The tubular structure is defined by a pair of body elements and has opposed longitudinal joints defined by overlapping portions of the body elements. One of the body elements overlaps the other of the body elements to define one of the joints and is overlapped by the other of the body elements to define the other of the joints.

FIELD OF THE INVENTION

The present invention relates to the field of heat exchangers.

BACKGROUND OF THE INVENTION

Heat exchangers are well known in the prior art and typically include apair of headers between which extend a plurality of tubes, and aplurality of fins interleaved between the tubes. An exemplary heatexchanger of the prior art is illustrated, partially conceptually, inFIG. 1. Often, the tubes are extruded elements which are fitted intoapertures formed in the headers and sealed thereto by flux brazing. Thetubes can be multi-port aluminum extrusions, having a plurality ofdiscrete fluid passages defined lengthwise of the tube. The tubes canalso be seam-welded tubes or extruded tubes having a single longitudinalinterior passage. In the latter case, to improve heat transfercharacteristics it is known to push or draw through the tube an elongateturbulizer of expanded metal or the like. The headers are often formedof a tubular part in which the apertures are defined and which isdefined by a pair of trough-shaped or channel elements, and a pair ofcaps which close the ends of the tubular part. Often, the trough-shapedelements and caps are brazed or welded together. The trough-shapedelements are often of differing dimensions, such that the longitudinalperipheral edges of one of the trough-shaped elements fit within thelongitudinal peripheral edges of the other, as shown in FIG. 2. Thisfacilitates fixturing during the brazing operation. The channel elementscan be self-fixturing, i.e. snap-fittable within one another, or anexternal fixture can be utilized.

SUMMARY OF THE INVENTION

An improved heat exchanger, said heat exchanger being of the typeincluding a pair of headers and a plurality of tubes extending betweenand fluidly connecting the headers, forms one aspect of the invention.The improvement comprises: a tubular structure for and defining in parteach of said headers, the tubular structure being defined by a pair ofbody elements and having opposed longitudinal joints defined byoverlapping portions of the body elements. One of the body elementsoverlaps the other of the body elements to define one of the joints andis overlapped by the other of the body elements to define the other ofthe joints.

According to another aspect of the invention, one of the body elementscan have an aperture for each tube; and each tube can interface with theother of the body elements in a single butt joint.

According to another aspect of the invention, the body elements can bechannels of arcuate profile with longitudinal edge portions that definethe overlapping portions; and measured in the direction by which thelongitudinal edge portions of the other of the body elements arespaced-apart from one another, an outer width of each tube can besubstantially equal to the distance by which said longitudinal edgeportions are spaced-apart.

An improved heat exchanger selected from the group including condensersand evaporators for automotive air conditioners and automotive oilcoolers and radiators forms another aspect of the invention. The heatexchanger is of the type including a pair of headers and a plurality oftubes extending between and fluidly connecting the headers. Theimprovement comprises: a cover and a pan interfitted with and brazed tothe cover to define each tube.

According to another aspect of the invention, a tubular structure can beprovided for and define in part each of said pair of headers; and thetubes can be brazed to the headers.

According to another aspect of the invention, the tubular structure canbe defined by a pair of body elements of arcuate profile brazedtogether.

According to another aspect of the invention, in each tube a turbulizercan be provided, the turbulizer including a pair of coplanar baseflanges dimensioned to centre the turbulizer in the tube.

An improved turbulizer, of the type for use in a tube formed ofcooperating portions brazed together, forms another aspect of theinvention. The improvement comprises: a pair of coplanar flangesdimensioned to centre the turbulizer in the tube in use.

A method for constructing a heat exchanger forms another aspect of theinvention. The heat exchanger is of the type including a pair of headersand a plurality of tubes extending between and fluidly connecting theheaders. The method comprises the steps of: for each header, providing apair of body elements each formed of brazing clad material; and brazingthe body elements together such that the headers each have opposedlongitudinal joints defined by overlapping portions of the bodyelements, one of the body elements overlapping the other of the bodyelements to define one of the joints and being overlapped by the otherof the body elements to define the other of the joints.

According to another aspect of the invention: for each tube, a tubularassembly formed of brazing clad material can be provided; one of thebody elements can have an aperture formed therein for each tube and thetubular assembly for each tube can be fitted into the apertures formedfor said each tube; and the body elements and the tubular assemblies canbe brazed together to form said heat exchanger.

According to another aspect of the invention, each tubular assembly caninterface with the other of the body elements in a single butt joint.

According to another aspect of the invention, the body elements can bechannels of arcuate profile with longitudinal edge portions that definethe overlapping portions; and in the heat exchanger, measured in thedirection by which the longitudinal edge portions of the other of thebody elements are spaced-apart from one another, an outer width of eachtube can be substantially equal to the distance by which saidlongitudinal edge portions are spaced-apart.

A method of constructing a heat exchanger, selected from the groupincluding condensers and evaporators for automotive air conditioners andautomotive oil coolers and radiators, is disclosed. The heat exchangeris of the type including a pair of headers and a plurality of tubesextending between and fluidly connecting the headers. The methodcomprises the steps of: for each header, providing a tubular structureformed of brazing clad material, the tubular structure having anaperture formed therein for each tube; for each tube, providing a coverand a pan, both formed of brazing clad material and fitting the pan intothe cover to form a tubular assembly; fitting the tubular assembly foreach tube into the apertures formed for said each tube; and brazing thetubular structures, the covers and the pans together.

According to another aspect of the invention, for each tubular structurecan be provided a pair of body elements each formed of brazing cladmaterial, one of the body elements defining the apertures for said eachtubular structure; and the body elements can be fitted together to formsaid tubular structure, and brazed to one another when the tubularstructures, the covers and the pans are brazed together.

According to another aspect of the invention, for each tube a turbulizercan be provided and fitted into the cover provided for said each tube toform a tube subassembly, into which tube subassembly the pan providedfor said each tube is fitted to form the tubular assembly.

According to another aspect of the invention, each turbulizer can beprovided with a pair of coplanar flanges dimensioned to centre said eachturbulizer in the tube for which it is provided.

According to another aspect of the invention: each of the pan and covercan include a body plate and a pair of peripheral flanges extending fromthe body plate; and prior to assembly of the pan and cover, theturbulizer can be inserted into the cover, with the flanges seatedagainst the cover body plate.

An improved heat exchanger forms another aspect of the invention. Theheat exchanger is of the type including a pair of headers and aplurality of tubes extending between and fluidly connecting the headers.The improvement comprises: a cover and a pan interfitted with and brazedto the cover to define each tube. In each tube a turbulizer is provided,the turbulizer including a pair of coplanar base flanges dimensioned tocentre the turbulizer in the tube.

According to yet another aspect of the invention, a tubular structurecan be provided for and define in part each of said pair of headers, thetubular structure being defined by a pair of body elements brazedtogether.

The invention permits the construction of heat exchangers of relativelyhigh performance and durability at relatively low cost. Otheradvantages, features and characteristics of the present invention, aswell as methods of operation and functions of the related elements ofthe structure, and the combination of parts and economies ofmanufacture, will become more apparent upon consideration of thefollowing detailed description and the appended claims with reference tothe accompanying drawings, the latter being briefly describedhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective, partially conceptual view of a heat exchangeraccording to the prior art;

FIG. 2 is a top view of the structure of FIG. 1;

FIG. 3 is a partial perspective view of a heat exchanger according to anexemplary embodiment of the invention;

FIG. 4 is a perspective view of a cap portion of the structure of FIG.3;

FIG. 5 is a cross-sectional view of a portion of the structure of FIG.3;

FIG. 5A is a simplified view of a portion of FIG. 5;

FIG. 6 is a view similar to FIG. 5 of the structure of FIG. 1;

FIG. 6A is a simplified view of a portion of FIG. 6;

FIG. 7 is a cross-sectional view of a portion of a tube of the structureof FIG. 3;

FIG. 8 is a cross-sectional view of another portion of a tube of thestructure of FIG. 3;

FIG. 9 is a cross-sectional view of a tube of the structure of FIG. 3;

FIG. 10 is an enlarged view of encircled area 10 of FIG. 9; and

FIG. 11 is a view, similar to FIG. 2, of a pair of heat exchangersaccording to a further exemplary embodiment of the invention disposed instacked relation.

DETAILED DESCRIPTION

An improved heat exchanger 20 forms one aspect of the invention and isillustrated in partial perspective in FIG. 3. For greater certainty, itshould be understood that the illustrated heat exchanger 20 is anexemplary embodiment, only, and is not to be construed as limiting inany way to the scope of the invention.

Exchanger 20 will be seen to be of the general type including a pair ofheaders 22 (only one shown); a plurality of tubes 24 extending betweenand fluidly connecting the headers 22; and a plurality of fins 26interleaved between the tubes 24. The exchanger 20 shown will further beseen to be of the two pass type, with inlet 28 and outlet 30 spigotsdisposed at opposite ends of the same manifold or header 22, whichheader 22 is segmented by an intermediate plate (shown in phantom anddesignated with reference numeral 32) to avoid direct flow between theinlet 28 and outlet 30.

The improvement resides in various features of construction of theheaders 22 and tubes 24, and the interconnection therebetween, all asdescribed hereinafter in detail.

With reference to FIGS. 3 and 5, the headers 22 each comprise a pair ofbody elements 34,36 and a pair of caps 38. The body elements 34,36 areroll-formed or stamped channels or troughs of arcuate profile withlongitudinal edge portions 40 and are formed out of braze clad aluminumof 1.0 mm thickness. One of the elements 34 has a plurality of apertures136 punched or otherwise formed therein for receiving the tubes 24, asdiscussed fully hereinafter. The other of the elements 36 has thespigots 28,30 extending therefrom, and is provided with notches 42 atits ends and an intermediate slot 44. The caps 38 are planar elementsformed out of 3.0 mm unclad aluminum sheet material. When assembled, thepair of body elements 34,36 define a tubular structure 46, the ends 48of which are occluded by respective caps 38. Tabs 50 on the caps 38register with the notches 42. A further “cap” has its tab 50 in registerwithin the intermediate slot 44 and defines the intermediate plate 32 inthis condenser 20. To form header 22, the body elements 34,36 and caps38 are assembled together and exposed to brazing conditions in a brazingfurnace (not shown). The caps 38 “master” the joint, such thatdimensional issues are controlled by the cap, which is advantageous fromthe standpoint of manufacturability.

The completed header 22 illustrated is characterized in the presence ofopposed longitudinal joints 52,54 defined by overlapping portions 40 ofthe body elements 34,36. More specifically, one of the body elements34,36 overlaps the other of the body elements 34,36 to define one of thejoints 52 and is overlapped by the other of the body elements to definethe other 54 of the joints, as shown in FIG. 5. In the illustratedembodiment, the portions 40 overlap one another over a distance of about3.0 mm, to provide for a good seal in the joints 52,54. This “overlapand underlap” arrangement of the body elements 34,36 is advantageous ascompared to the conventional “overlap and overlap” arrangement (i.e ofFIG. 2) in that, by so modifying the geometry, with a substantiallysimilar amount of material, a tube having a greater cross-sectional areais obtained.

This is evident from a comparison of the structure of FIG. 5, whichshows a cross section of the header of FIG. 3 and a portion of a tube,and the structure of FIG. 6, which shows the analogous structure of aheat exchanger of similar size constructed according to the conventionaloverlap and overlap arrangement, which has a cross-sectional area only84% as large as that of FIG. 5, as indicated by FIGS. 5A, 6A. Thegreater area of the FIG. 5 structure, of course, advantageously reducespressure drop.

A yet further advantage of the “overlap and underlap” arrangement isassociated with the elegant and efficient manner in which multiple heatexchangers 20 can be stacked together, as shown in FIG. 11, with onlythree material thicknesses separating the manifold interiors, incontrast to the four material thicknesses associated with theconventional “overlap and overlap”. This has advantages in terms of theoverall width of a stacked heat exchanger, which can be advantageous inautomotive applications, as the space available in the enginecompartment or air box of a vehicle is limited.

With regard to the tubes 24, the tubes 24 of the disclosed embodimentare defined by a cover 56 and a pan 58, as shown in FIGS. 7 and 8,respectively. The cover 56 is formed of braze clad aluminum of 0.4 mmthickness and includes a body plate 60 and a pair of peripheral flanges62 extending from the body plate 60. The pan 58 is also formed of brazeclad aluminum of 0.4 mm thickness and includes a body plate 64 and pairof peripheral flanges 66.

The pan 58 is dimensioned to fit within the cover 56. The assembled, butnot brazed, pan 58 and cover 56 together define a tubular assembly. Onceexposed to brazing conditions, the pan 58 and the cover 56 braze to oneanother to define a tube 24.

This tube construction is advantageous, in that it permits a fluxlessbraze joint to be created between the tubes 24 and the headers 22, evenin association with manifolds constructed out of relatively thin gaugematerial, such as 0.020″-0.070″ inch material, as the brazing materialon the tubes accommodates the relatively lesser amounts of brazingmaterial provided on the headers in thin-wall construction.

In assembly of the condenser 20, the tubular assembly for each tube 24is fitted into the apertures 136 formed for said each tube 24 in thebody elements 34, as shown in FIG. 5, and the entire assembly issubjected to brazing conditions in a brazing furnace, to braze the pans58 to the covers 56, the body elements 34,36 to one another, the caps 38to the body elements 34,36 and the tubes 24 to the headers 22. Flaredmaterial 70, resultant from the punching operation by which theapertures 136 in the body elements 34 were formed, can be maintained, toprovide a relatively large lap joint for tube 24-header 22 braze joint.This can also facilitate tube entry.

Recalling that one 34 of the body elements has an aperture 136 for eachtube 24, the illustrated tube-header joint is characterized in that eachtubular assembly interfaces with the other 36 of the body elements in asingle butt joint, and is further characterized in that, measured in thedirection by which the longitudinal edge 40 portions of the other 36 ofthe body elements are spaced-apart from one another, an outer width y ofeach tube 24 is substantially equal to the distance by which saidlongitudinal edge portions 40 are spaced-apart. Importantly, all thingsremaining equal, this manner of tube-header joinder provides for agreater inlet size than that obtained via the conventional “overlap andoverlap” arrangement, as evidenced by FIGS. 5, 6, wherein, from a common10 mm tube size, inlet diameter z is shown to increase from 8.4 mm to9.4 mm, that is, the thickness of the material forming the bodyelements, through the use of the “under and overlap” configuration.

A further advantage of the pan 58 and cover 56 tube construction overextruded tubes is that it permits the ready introduction of a turbulizer80 into the tube, as shown in FIG. 9. To do so, the turbulizer 80 merelyneeds to be fitted into one of the pan 58 and the cover 56 beforeassembly of the pan and cover.

The turbulizer 80 illustrated in FIG. 9 is notable in the presence of apair of coplanar flanges 82 which extend outwardly from the base of theturbulizer 80. With the exception of the flanges 82, the turbulizer 80can be of any conventional construction and, for example, can be of theexpanded metal or offset fin variety.

In assembly of the illustrated heat exchanger, prior to assembly of thepan 58 and the cover 56, the illustrated turbulizer 80 is inserted intothe cover 56, with the coplanar flanges 82 seated against the cover bodyplate 60 to form a tube subassembly (not shown). Once the turbulizer 80is so inserted, the pan 58 is fitted into the cover 56. Coplanar flanges82 are dimensioned to centre or locate the turbulizer 80 in the passagedefined by the assembled pan and cover 56,58, i.e. to space theoutermost corrugations of the turbulizer 80 from the inner tube wallsurfaces a distance equivalent to the spacing between the corrugations,so as to avoid undesirable bypass flow and dead zones and maximize heattransfer. Advantageously, the height of the turbulizer, i.e. theamplitude of the corrugations in the case of an offset fin turbulizer,is such that the pan 58 and cover 56 are both brazed thereto during thebrazing of the tubes. The pan 58 may bear against the coplanar flanges82 in the assembled tube, but relatively shorter flanges 66 on pan 58will maximize the likelihood of good braze joints between the turbulizer80, pan 58 and cover 56, with a commensurate effect on the resultantburst strength of tube 24.

A yet further advantage of the pan and cover tube construction is thatit permits fins 26 to be readily constructed out of unclad aluminumsheet, with the cladding on the pans and the covers providing brazingmaterial for the joinder of the fins 26 to the tubes 24 during thebrazing of the various components to one another.

While but two embodiments of the present invention have been hereinshown and described, it will be understood that various changes in sizeand shape of parts may be made.

For example, whereas in the illustrations, manifolds and tubes areconstructed out of sheet material of a common thickness, the manifoldsand tubes can be constructed out of materials of varying thicknesses.Tubes of varying widths can be utilized, and in the automotive fieldwill typically range between 10 mm (as illustrated) and 50 mm. Manifoldsof different cross-sections can also be utilized, as is clearly evidentfrom FIG. 11, wherein two manifolds of differing size are shown, and itshould be understood that the shape and size of the particular bodyelements employed impact on the cross-sectional area advantageassociated with the shift from overlap/overlap to overlap/underlapconfiguration.

Additionally, whereas the illustrated heat exchanger is of the two-passtype, it will be readily appreciated that single or multiple-passexchangers could similarly be constructed.

As well, whereas the illustrated turbulizer is shown in use in a pan andcover tube, it would also have usefulness elsewhere, such as in tubesformed of mating plate pairs, or in stacked dish structures.

Similarly, whereas only a single tab is shown on each cap, multiple tabscould be utilized, if desired.

Moreover, although fins are shown in FIG. 3, they could be omitted.

As well, whereas in the heat exchanger of FIG. 9, the tube is showninterfacing with the other body element (i.e. the body element that isnot the body element in which the apertures are provided) in a singlebutt joint, as is evident from FIG. 11, heat exchangers according toaspects of the invention can be manufactured with each tube interfacingonly with the body element through which the apertures are provided.

Further, it should be understood that manifolds for any heat exchangeror indeed any fluid core structure could be produced with the overlapand underlap structure shown. As well, turbulizers as described hereincould be provided in any flat tube. Further, the illustrated tube toheader joint is contemplated to have broad applicability in the contextof heat exchangers and similar core structures using clad tubes otherthan pan and cover tubes, such as seam-welded clad tubes. Further, thepan and cover tube construction is contemplated to have applicabilityin, the context of heat exchangers of various types including radiators,oil coolers and condensers and evporators for air conditioners.

Finally, but without limitation, it should be appreciated that themaintenance of the flared material at the header apertures is notnecessary, and might advantageously be removed in certain applications.

Accordingly, the invention should be understood as being limited only bythe claims appended hereto, purposively construed.

1. An improved heat exchanger, said heat exchanger being of the typeincluding a pair of headers and a plurality of tubes extending betweenand fluidly connecting the headers, the improvement comprising: atubular structure for and defining in part each of said headers, thetubular structure being defined by a pair of body elements and havingopposed longitudinal joints defined by overlapping portions of the bodyelements, wherein one of the body elements overlaps the other of thebody elements to define one of the joints and is overlapped by the otherof the body elements to define the other of the joints.
 2. An improvedheat exchanger according to claim 1, characterized in that: the one ofthe body elements has an aperture for each tube; and each tubeinterfaces with the other of the body elements in a single butt joint.3. An improved heat exchanger according to claim 1, wherein the bodyelements are channels of arcuate profile with longitudinal edge portionsthat define the overlapping portions; and measured in the direction bywhich the longitudinal edge portions of the other of the body elementsare spaced-apart from one another, an outer width of each tube issubstantially equal to the distance by which said longitudinal edgeportions are spaced-apart.
 4. A heat exchanger selected from the groupincluding condensers and evaporators for automotive air conditioners andautomotive oil coolers and radiators, the heat exchanger being of thetype including a pair of headers and a plurality of tubes extendingbetween and fluidly connecting the headers, the improvement comprising:a cover and a pan interfitted with and brazed to the cover to defineeach tube.
 5. An improved heat exchanger according to claim 4, wherein:a tubular structure is provided for and defines in part each of saidpair of headers; and the tubes are brazed to the headers.
 6. An improvedheat exchanger according to claim 5, wherein the tubular structure isdefined by a pair of body elements of arcuate profile brazed together.7. An improved heat exchanger according to claim 4, characterized inthat in each tube a turbulizer is provided, the turbulizer including apair of coplanar base flanges dimensioned to centre the turbulizer inthe tube.
 8. An improved turbulizer of the type for use in a tube formedof cooperating portions brazed together, the improvement comprising: apair of coplanar flanges dimensioned to centre the turbulizer in thetube in use.
 9. A method for constructing a heat exchanger, the heatexchanger being of the type including a pair of headers and a pluralityof tubes extending between and fluidly connecting the headers, themethod comprising the steps of: for each header, providing a pair ofbody elements each formed of brazing clad material; and brazing the bodyelements together such that the headers each have opposed longitudinaljoints defined by overlapping portions of the body elements, one of thebody elements overlapping the other of the body elements to define oneof the joints and being overlapped by the other of the body elements todefine the other of the joints.
 10. A method according to claim 9,wherein for each tube, a tubular assembly formed of brazing cladmaterial is provided; and one of the body elements has an apertureformed therein for each tube and the tubular assembly for each tube isfitted into the apertures formed for said each tube; and the bodyelements and the tubular assemblies are brazed together to form saidheat exchanger.
 11. A method according to claim 10, wherein each tubularassembly interfaces with the other of the body elements in a single buttjoint.
 12. A method according to claim 10, wherein the body elements arechannels of arcuate profile with longitudinal edge portions that definethe overlapping portions; and in the heat exchanger, measured in thedirection by which the longitudinal edge portions of the other of thebody elements are spaced-apart from one another, an outer width of eachtube is substantially equal to the distance by which said longitudinaledge portions are spaced-apart.
 13. A method of constructing a heatexchanger selected from the group including condensers and evaporatorsfor automotive air conditioners and automotive oil coolers andradiators, said heat exchanger being of the type including a pair ofheaders and a plurality of tubes extending between and fluidlyconnecting the headers, the method comprising the steps of: for eachheader, providing a tubular structure formed of brazing clad material,the tubular structure having an aperture formed therein for each tube;for each tube, providing a cover and a pan, both formed of brazing cladmaterial; and fitting the pan into the cover to form a tubular assembly;fitting the tubular assembly for each tube into the apertures formed forsaid each tube; and brazing the tubular structures, the covers and thepans together.
 14. A method according to claim 13, wherein: for eachtubular structure is provided a pair of body elements each formed ofbrazing clad material, one of the body elements defining the aperturesfor said each tubular structure; and the body elements are fittedtogether to form said tubular structure, and brazed to one another whenthe tubular structures, the covers and the pans are brazed together. 15.A method according to claim 13, wherein, for each tube, a turbulizer isprovided and fitted into the cover provided for said each tube to form atube subassembly, into which tube subassembly the pan provided for saideach tube is fitted to form the tubular assembly.
 16. A method accordingto claim 15, wherein each turbulizer is provided with a pair of coplanarflanges dimensioned to centre said each turbulizer in the tube for whichit is provided.
 17. A method according to claim 16, wherein: each of thepan and cover includes a body plate and a pair of peripheral flangesextending from the body plate; and prior to assembly of the pan andcover, the turbulizer is inserted into the cover, with the flangesseated against the cover body plate.
 18. An improved heat exchanger, theheat exchanger being of the type including a pair of headers and aplurality of tubes extending between and fluidly connecting the headers,the improvement comprising: a cover and a pan interfitted with andbrazed to the cover to define each tube, wherein, in each tube aturbulizer is provided, the turbulizer including a pair of coplanar baseflanges dimensioned to centre the turbulizer in the tube.
 19. Animproved heat exchanger according to claim 18, wherein a tubularstructure is provided for and defines in part each of said pair ofheaders, the tubular structure being defined by a pair of body elementsbrazed together.